There are a wide variety of wireless networks. A smart utility network (SUN) is a low data rate (40 kb/s to 1 Mb/s), low power wireless technology that is specifically designed to be used in utility metering applications, such as transmitting electric, gas, or water usage data from the meter(s) on the customer's premises to a data collection point (hub) operated for the utility. For example, meters can be installed for each house in a residential neighborhood, and then the data can be sent every 15 minutes from each meter to a poletop data collection point. This data collection point could then be connected by fiber, copper wire, or wirelessly to a central office which collects all the data for a region. Data can either be sent directly from each meter to the collection point (star configuration), or can be hopped from meter to meter until it reaches the collection point (mesh configuration).
There are different physical layers (PHY) modulation types that can be used for SUN communications including frequency shift keying (FSK), DSSS (direct sequence spread spectrum), and orthogonal frequency division multiplexing (OFDM). In a closed utility network the devices that are allowed into the network can be controlled by the utility or the network operator.
A network can also be set up in a mesh configuration where devices can communicate with neighboring devices rather than just with a hub. This helps to increase coverage since communication can be achieved even if the link directly to the hub is not good. However, this can increase the amount of traffic that goes through some devices since they have to include frame data from their neighbors as well as their own data. A mesh network can be appropriate for an urban or suburban area with a high density of meters and non-line-of-sight conditions between meters so that communication links between some meters and a hub is poor.
A star configuration is a configuration where a hub communicates directly with each meter. This configuration can be appropriate for rural environments when the density of meters is low so that there may not be a convenient neighbor to use as an intermediate hop. A mix between a star and mesh configuration can also be used in some deployments.
Since utility meters typically have a long life span, such as 20 years or more, there may be several different generations of meters deployed in a given utility network. The earlier generation deployed meters can be termed “legacy equipment” and be configured to only support FSK, while newer generation equipment may support higher data rate DSSS and/or OFDM in addition to FSK in what may be termed a “mixed modulation equipment” network. In a typical mixed modulation equipment embodiment, since multiple modulations cannot be simultaneously supported, the utility network will be forced to have all the devices communicate using FSK, at the low relative fixed data rate supported by FSK, such as 50 kb/s, 100 kb/s or 153 kb/s. In addition, more generally in wireless networks, mixed modulations can be used for purposes other than smart utility networks such as data, video, or voice transmission.